Fog producing device



Dec. 25, 1945. w, CAUSER 2,391,616

FOG PRODUCING DEVICE Filed Oct. 21, 1943 MWYW Patented Dec. 25,1945

. FOG PRODUCING DEVICE Herbert W. Causer.

Factory Mutual Weymouth, Mass., asslgnor to Research Corporation,Boston,

Mass, a corporation of Massachusetts Application October 21, 1943,Serial No. 507,068

7 Claims.

This invention relates to a device for producing a fog of waterparticles or other material for use in extinguishing fires or as ascreen or for other purposes, in contradistinction to an ordinarysprinkler nozzle which merely distributes water in relatively largeglobules over a wide area. The invention is particularly useful inextinguishing fires in vats or tanks of kerosene, fuel oil, rubbercement, lacquer and other inflammable liquids, which are diflicult toextinguish but which can be smothered by replacing the surrounding airwith a fog of material incapable of supporting combustion. For examplethe devices of the present invention may be used to advantage in lieu ofthe spray nozzles disclosed in Patent 2,283,775 of Norman J. Thompson.

Objects of the invention are to produce a device of the characterreferred to which is'simple and economical to manufacture, which isreliable and eificient in use, which does not require excessively highpressure, which does not clog so easily as the old spray nozzles, whichaffords practically uniform distribution of fog throughout thecross-sectional area of the delivered stream, which permits the streamto be confined to a comparatively small cross-sectional area, and whichis generally superior to the spray nozzles of the prior art.

The device of the present invention comprises a flaring bafile which ispreferably conical, that is which has an outer surface approximatingthat of a cone, the baflle having slots extendin from its larger endtoward its smaller end together with openings between the bottoms of theslots and the smaller end, so that when the smaller end of the bafile isheld in line with a jet of water or the like, the jet is subdivided intosmaller jets which pass through the slots and openings and then impingeon each other to form a fog the boundary of which is substantiallydefined by water deflected along the outer surface of the baffle in theshape of a cone. Preferably the walls of the slots lie substantially inplanes which contain the axis of the bafile and the axes of theaforesaid openings are approximately parallel to the same axis, wherebythe water passes through the slots and openings with less resistance andless deflection. Somewhat better results are obtained by locating theopenings opposite the bottoms of certain of the slots so that eachopening and adjacent slot are disopsed in the same axial plane. In thepreferred embodiment the slots have approximately uniform width from endto end, in which case the fingers between the slots are keystone shaped.In order to confine the fog to a well-defined cone and to cause the fogto flow as a directed stream, the flare of the bafile should be lessthan approximately a right-angle, that is the angle subtended byopposite sides of the baffle should not greatly exceed The slots may bemore or less elongate but opposite slots together preferably span atleast approximately one-third the largest diameter of the bafiie. Thatis looking at the end of the baffle along its axis the apparent lengthsof opposite slots added together are at least approximately equal toonethird the diameter of the baffle at the larger end. By making thebaffle hollow thesubdivided jets passing through the slots and openingsrespectively impinge upon each other Within the baffle, so that theinterior of the conical baffle constitutes an atomizing chamber.

In a more specific aspect the invention involves a combination of theaforesaid baflle with a nozzle.

directed toward the smaller end of the baflie and means to join thenozzle and the bafiie in predetermined spaced relationship so that thejet issuing from the nozzle is distributed approximatelyuniformly aroundthe outer periphery of the bafiie. Preferably the means which join thenozzle and bafile is shaped to form the apex of the cone, the slottedpart of the baffle comprising a truncated cone having its base seatedagainst the aforesaid apex.

For the purpose of illustration a typical embodiment is shown in theaccompanying drawing in which Fig. l is a full-sized side view of atypical embodiment, with a part broken away;

Fig. 2 is an enlarged end view;

Fig. 3 is a sectional view on line 3-4 of Fig. 2; but on the same scaleas Fig. 1; and

Fig. 4 is a sectional view on line 3-4 of Fig. 2 of the bafile.

The particular embodiment of the invention chosen for the purpose ofillustration comprises a nozzle I having a. reduced outlet 2 and athreaded end 3 adapted to be screwed into a pipe coupling, incombination with abafile comprising a hollow truncated cone 4. The coneis joined to the nozzle by means of two arms 6 which meet in a. taperedhead 1 which constitutes the apex of the bafile. The end 8 of thetruncated cone seats against the bottom of the apex 1 and is secured inposition by brazing. In the illustration the nozzle is closed by a capl2 held in place by two struts through opening I I, and a fusible link Min wellknown manner, but these parts are not essential to the presentinvention.

IS, an adjusting screw ll extending,

The truncated cone is provided with slots I6 extending from the largerend towards the smaller end and also-with circular openings I'I. Theslots and openings should have sharp edges on top to permit the water toenter with less turbulence and therefore in greater quantity.

While the dimensions of the parts may be varied to some extent,excellent results have been obtained with those shown in the drawingwhich are approximately as follows: length of truncated cone-18 mm.,length of apexl2 mm., making a total length of the conical baifie 30mm.; the maximum diameter of the truncated cone-30 mm.; the length ofthe slots measured along the outer surface of the truncated conemm.; thewidth of the slots-2 mm.; the width of the fingers between the slots,measured near the bottoms of the slots (that is the closed ends of theslots)-2 mm.; the diameter of the outlet 26 mm.; the distance from theoutlet 2 to the apex of the bathemm.; and the diameter of the openings"-3 mm. As shown in the drawing the flare of the truncated cone isapproximately In installations where these devices are mounted over atank or vat they are preferably distributed around the periphery of thetank or vat as disclosed in the aforesaid patent, about three feet apartand about six feet above the level of the liquid in the tank or vat. Thesubdivided jets which pass through the slots impinge upon each other andupon the jets flowing through the openings ll, whereby the liquid isbroken up into a fog which, while very finely divided, continues to flowin the same general direction to form a cone which isentirely filledwith fog of approximately uniform distribution.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. A fog device for use with a water jet to produce a conical stream offog, comprising a flaring baffle having a plurality of radial fingerswith slots therebetween of approximately uniform width extending fromits larger end toward its smaller end and openings between the bottomsof the slots and said smaller end, said fingers extending away from saidsmaller end and throughout their extent having their center linesdivergent relative to one another.

2. A fog device for use with a water jet to produce a conical stream offog, comprising a flaring slots therebetween of approximately uniform.

width extending from its larger end toward its smaller end and openingsbetween the bottoms of the slots and said smaller end, opposite slotstogether spanning at least approximately onethird the largest diameterof the bailie, said fingers extending away from said smaller end andthroughout their extent having their center lines divergent relative toone another.

4. A fog producing device according to claim 1 further characterized inthat the conical bailie is hollow to form an atomizing chamber in whichthe subdivided jets passing through the slots and openings respectivelyimpinge upon each other.

5. A fog producing device according to claim 1. further characterized bya nozzle directed toward the smaller end of the baflle and means to jointhe nozzle and bafile in predetermined spaced relationship, said meansbeing shaped to form the apex of the conical baflle.

6. A fog producing device according to claim 1 further characterized bya nozzle directed toward the smaller end of the bafile and means to jointhe nozzle and baille in predetermined spaced relationship, said meansbeing shaped to form the apex of the conical baffle and the bafliecomprising a truncated cone having its base seated against said apex. p

7. A fog device for use with a water jet to produce a conical stream offog, comprising a flaring baffle having a plurality of radial fingerswith slots therebetween of approximately uniform width extending fromits larger end toward its smaller end and openings between the bottomsof the slots and said smaller end, said fingers extending away from saidsmaller end and throughout their extent having their center linesdivergent relative to one another, and the walls of said openings beingparallel with the axis of the water jet and the entrant edges of theopenings being sharp.

HERBERT W.'CAUSER.

